Buggy code:
public class AspectJExpressionPointcut extends AbstractExpressionPointcut implements ClassFilter , IntroductionAwareMethodMatcher , BeanFactoryAware { private static final Set DEFAULT_SUPPORTED_PRIMITIVES = new HashSet ( ) ; private static final Log logger = LogFactory . getLog ( AspectJExpressionPointcut . class ) ; private final Map shadowMapCache = new HashMap ( ) ; private PointcutParser pointcutParser ; private Class pointcutDeclarationScope ; private String [ ] pointcutParameterNames = new String [ 0 ] ; private Class [ ] pointcutParameterTypes = new Class [ 0 ] ; private BeanFactory beanFactory ; private PointcutExpression pointcutExpression ; public AspectJExpressionPointcut ( ) { } public AspectJExpressionPointcut ( Set supportedPrimitives ) { } public AspectJExpressionPointcut ( Class declarationScope , String [ ] paramNames , Class [ ] paramTypes ) { } public void setPointcutDeclarationScope ( Class pointcutDeclarationScope ) { } public void setParameterNames ( String [ ] names ) { } public void setParameterTypes ( Class [ ] types ) { } public void setBeanFactory ( BeanFactory beanFactory ) { } public ClassFilter getClassFilter ( ) { } public MethodMatcher getMethodMatcher ( ) { } private void checkReadyToMatch ( ) { } private PointcutExpression buildPointcutExpression ( ) { } private String replaceBooleanOperators ( String pcExpr ) { } public PointcutExpression getPointcutExpression ( ) { } public boolean matches ( Class targetClass ) { } public boolean matches ( Method method , Class targetClass , boolean beanHasIntroductions ) { } public boolean matches ( Method method , Class targetClass ) { } public boolean isRuntime ( ) { } public boolean matches ( Method method , Class targetClass , Object [ ] args ) { } protected String getCurrentProxiedBeanName ( ) { } private boolean matchesIgnoringSubtypes ( ShadowMatch shadowMatch ) { } private boolean matchesTarget ( ShadowMatch shadowMatch , Class targetClass ) { } private void bindParameters ( ProxyMethodInvocation invocation , JoinPointMatch jpm ) { } private ShadowMatch getShadowMatch ( Method targetMethod , Method originalMethod ) { } @ Override public boolean equals ( Object other ) { } @ Override public int hashCode ( ) { } @ Override public String toString ( ) { <START_BUG> StringBuffer sb = new StringBuffer ( ) ; <END_BUG> sb . append ( "AspectJExpressionPointcut:<seq2seq4repair_space>" ) ; if ( ( ( this . pointcutParameterNames ) != null ) && ( ( this . pointcutParameterTypes ) != null ) ) { sb . append ( "(" ) ; for ( int i = 0 ; i < ( this . pointcutParameterTypes . length ) ; i ++ ) { sb . append ( this . pointcutParameterTypes [ i ] . getName ( ) ) ; sb . append ( "<seq2seq4repair_space>" ) ; sb . append ( this . pointcutParameterNames [ i ] ) ; if ( ( i + 1 ) < ( this . pointcutParameterTypes . length ) ) { sb . append ( ",<seq2seq4repair_space>" ) ; } } sb . append ( ")" ) ; } sb . append ( "<seq2seq4repair_space>" ) ; if ( ( getExpression ( ) ) != null ) { sb . append ( getExpression ( ) ) ; } else { sb . append ( "<pointcut<seq2seq4repair_space>expression<seq2seq4repair_space>not<seq2seq4repair_space>set>" ) ; } return sb . toString ( ) ; } private class BeanNamePointcutDesignatorHandler implements PointcutDesignatorHandler { private static final String BEAN_DESIGNATOR_NAME = "bean" ; public String getDesignatorName ( ) { } public ContextBasedMatcher parse ( String expression ) { } } private class BeanNameContextMatcher implements ContextBasedMatcher { private final NamePattern expressionPattern ; public BeanNameContextMatcher ( String expression ) { } public boolean couldMatchJoinPointsInType ( Class someClass ) { } public boolean couldMatchJoinPointsInType ( Class someClass , MatchingContext context ) { } public boolean matchesDynamically ( MatchingContext context ) { } public FuzzyBoolean matchesStatically ( MatchingContext context ) { } public boolean mayNeedDynamicTest ( ) { } private FuzzyBoolean contextMatch ( Class targetType ) { } private boolean matchesBeanName ( String advisedBeanName ) { } } }

Fix:
StringBuilder sb = new StringBuilder ( ) ;